Packaging device

ABSTRACT

A method of and a device for folding a bottom of a package, which includes a sleeve of packaging material with a transversal seal in the end of the bottom forming portion of the package, the portion having the shape of a fin. The method includes folding the fin and forming primary flaps, breaking corners on the folded fin between the primary flaps and the edge between the part of the sleeve forming the bottom and the rest of the sleeve, such that secondary flaps are folded in between the primary flaps and the fin, the secondary flaps thereby being folded essentially towards each other, folding the primary flaps towards each other, and pressing the primary flaps towards the remaining part of the bottom forming part of the sleeve.

This application is the National Phase of International ApplicationPCT/SE2003/001819, filed Nov. 24, 2003, published under PCT Article21(2) in English as WO 2004/054790 A1. International ApplicationPCT/SE2003/001819 claimed priority to Swedish Application 0203690-3,filed Dec. 13, 2002.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method and a device for folding thebottom of a package as well as a package.

BACKGROUND ART

A variety of different packaging solutions are currently used fordifferent types of liquids. The packages, or containers, can be made ofe.g. aluminium, plastic or laminated paper. Different packagingmaterials and different container designs could be appropriate fordifferent types of liquids.

The choice of packaging material is also based on the container design.One type of container which is particularly suitable for non-carbonatedbeverages consists of a sleeve, a bottom and a top, where the differentparts are not necessarily made of the same material. For instance, thesleeve and the bottom can be integrally manufactured of laminated paperand the top be injection moulded in plastic. The bottom is, forinstance, formed by sealing one end of the sleeve and then folding itsuch that a square or rectangular bottom is created. Such a container isdisclosed in EP-B1-0 960 014 and WO 98/32666. A similar design isdisclosed in EP-A1-0 862 980. Such containers can be used for beveragesthat are meant to be drunk directly from the container. When holding acontainer in one's hand, it is often most comfortable if the containeris round in cross-section. However, known containers with folded bottomsare square or rectangular in cross-section. To fold the bottom such thatthe cross-section of the sleeve is essentially round is not feasibleusing known techniques.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a folding of the bottomof a package such that the package obtains an essentially roundedcross-section.

Thus, according to the method of the invention the bottom of a packageis folded, which package comprises a sleeve of packaging material with atransversal seal in the end of the bottom forming portion of thepackage, said portion having the shape of a fin, using the steps of

folding the fin such that primary flaps are created at the transversalends of the fin,

breaking corners on the folded fin in the boundary regions between theprimary flaps and the edge between the part of the sleeve forming thebottom and the rest of the sleeve, such that secondary flaps are foldedin between the primary flaps and the remaining part of the fin, thesecondary flaps on the same primary flap thereby being foldedessentially towards each other,

folding the primary flaps towards each other, and

pressing the primary flaps towards the remaining part of the bottomforming portion of the sleeve.

This folding method has the advantage of being fast and efficient. Itaffords the package a stable bottom of a shape that gives the rest ofthe sleeve an essentially rounded cross-section, making it convenientfor a consumer to hold. This way of folding the bottom can also be usedfor the forming of packages having a cross-section formed by twocircular halves connected by two essentially parallel straight lines.The distance between the straight lines and the rounded side makes iteasy for the consumer to grip the package even containing large volumes.

According to a preferred embodiment of the invention, the bottom of thepackage is folded into an octagonal shape. This gives the advantage ofproviding the package with a bottom shape which gives the sleeve arounded cross-section.

Further, the sleeve can have a longitudinal seal and the fin ispreferably then pre-folded away from the longitudinal seal prior to theprimary flap-creating folding step.

This gives the advantage of making the rest of the folding easier toperform, since the direction of the folding of the fin is thenpredetermined. Thus, this ascertains that the fin is not bent in themiddle and folded in different directions towards the part of the sleeveforming the bottom. The pre-folding away from the longitudinal seal isthe easiest way to fold the fin, since it is then not folded over thedouble layers of package material in the longitudinal seal.

The fin can be heated during the pre-folding to reduce the risk of anycracks occurring in the packaging material. This increases the safetymargin in respect of ensuring that the package contents do not come incontact with the outside of the package or any other layers in thepackaging material than the one closest to the contents, which otherwisecould lead to a quality deterioration of the contents.

The fin can be heated in a number of locations, where it is arranged tobe sealed during the pressing down-step, along its length prior to thepressing-down step. This gives the advantage of providing an easy way ofholding the fold together, since the heating melts some of the surfacepackaging material, which is then sealed to the parts of the fin pressedagainst it during the pressing-down step.

A first partible external forming tool can retain the package during thepressing-down step. This is advantageous since it adds stability and thepressing down can be performed with greater power, thus ensuring a tightfold.

The first partible external forming tool can be opened and closed alongthe contours of a parallelogram. This has the advantage of saving spacewhen opening the forming tool. It is also advantageous since it is afast and convenient way of operating the forming tool, since the openingmovement of the tool is utilised to the same extent along the wholeheight of-the package.

The invention also concerns a device for folding the bottom of apackage, which package comprises a sleeve of packaging material with atransversal seal in the bottom in the shape of a fin, which devicecomprises

a first folding unit for folding the fin such that flaps are created atthe transversal ends of the fin,

a breaking unit for breaking corners on the folded fin in the boundaryregions between the primary flaps and the edge between the part of thesleeve forming the bottom and the rest of the sleeve, such thatsecondary flaps are folded in between the primary flaps and theremaining part of the fin, the secondary flaps on each side of eachprimary flap thereby being folded essentially towards each other,

a second folding unit for folding the flaps against each other, and

a pressing unit for pressing the flaps towards the remaining part of thebottom forming part of the sleeve. The device is preferably arranged forfolding the bottom into an octagonal shape. This device has the aboveadvantages of the previously described method.

The breaking unit can have four knives arranged in positions essentiallyat the corners of a rectangle, such that each respective knife is ableto operate on a respective side of a respective flap. This has theadvantage of making it possible to perform the breaking simultaneouslyon both sides of both transversal end flaps in a fast and efficientmanner.

The sleeve can have a longitudinal seal and the device can comprisemeans for pre-folding the fin away from the longitudinal seal, and thedevice can have first means for heating the pre-folded fin and reducingthe risk of cracks occurring in the packaging material. The means forpre-folding the fin and the first means for heating the pre-folded fincan be arranged in a first sub-assembly, which gives the advantage ofmaking it possible to perform the pre-folding and heating essentiallysimultaneously, thereby making it possible for the device to work with ahigher efficiency.

At least one first cylinder can be connected to a respective at leastone first cam wheel and be arranged to control the movement of the firstsub-assembly and members thereof. This gives the advantage of providingan easy and reliable way of controlling the movements.

The device can comprise a first pair of brackets for holding thebreaking unit and a second pair of brackets for holding the firstfolding unit, which brackets each are provided with cam surfaces,wherein one shaft is arranged on each side of the pairs to move alongthe cam surface on each side of the pairs and thereby simultaneouslycontrol the movement of the breaking unit and the first folding unit.This gives the advantage of providing a simple way of controlling themovement of the two units and ensuring that they are moved in thedesired way in relation to each other as well as the package. It alsomakes the construction of the device more simple since the two units canbe driven and controlled by a common drive unit to which the shafts areconnected.

The device can comprise at least one flap support which is arranged toflatten the primary flaps against the folding unit. This gives theadvantage of ensuring an attractive appearance of the final foldedpackage bottom.

The device can comprise second means for heating a number of locationson the folded fin along its length, on which locations the fin isarranged to be sealed, to such an extent that a plastic layer present inthe packaging material is at least partly melted. This gives theadvantage of making it easy to obtain an efficient sealing of the foldedbottom.

The at least one flap support can be arranged to hold the flaps duringthe heating. This ensures that the flaps are in the correct positionduring heating so that it is easy for the second heating means to comeclose to the fin and heat it in the desired locations.

The breaking unit, the folding unit and the second means for heating thefin can be arranged in a second sub-assembly. This makes it possible toperform these three operations during a very short time interval, andlet the units operate on the package during partially overlapping timeintervals. This gives the advantage of making the device faster and moreefficient.

At least one second cylinder can be connected to a respective at leastone second cam wheel and be arranged to control the movement of thesecond sub-assembly and members thereof. This gives an easy andefficient way of controlling the movements.

The device can comprise a first partible forming tool for supporting thepackage during the pressing down of the flaps towards the part of thebottom forming part of the sleeve. This adds stability to the packageand makes it possible to use a greater power in the pressing unit, whichmakes the sealing of the folding more secure.

Each part of the first partible forming tool can be arranged to beopened and closed essentially along the contour of a parallelogram. Thishas the advantage of saving space when opening the forming tool. It isalso advantageous since it is a fast and convenient way of operating theforming tool, since the opening movement of the tool is utilised to thesame extent along the whole height of the package.

The first partible forming tool, the pressing unit and the secondfolding unit can be arranged in a third sub-assembly. This has theadvantage of making it possible to press down the primary flaps verysoon after the folding thereof, thus making the pressing down moresecure than if the package would have to be moved before thepressing-down-step.

At least one third cylinder can be connected to a respective at leastone third cam wheel and be arranged to control the movement of the thirdsub-assembly and members thereof. This provides an easy, efficient andreliable way of controlling the movements.

At least one cylinder can be arranged to control the movement of atleast one moving part comprised in the device, said at least onecylinder being connected to one end of a respective at least one lever,which lever in turn is fixed in the other end and is arranged to abutagainst a respective rotating cam wheel, and the movement of which iscontrolled by the same. This gives the advantage of making it possibleto control the movement of the moving part in an simple, efficient andreliable manner.

The at least one cylinder can be arranged to pull the lever towards thecentre of the cam wheel. This means that the moving part controlled bythe cylinder, when the cam wheel does not push the cylinder, is driventowards a position closer to the package or the other half of the movingpart. This also means that the only force pushing the moving partstowards the packages or other halves—or, so to speak, their activepositions—is the force of the cylinders, which does not have to be verygreat to achieve the desired folding steps. This is advantageous in thecase where, for instance, some kind of tool such as a screw driver hasgot caught in the device by mistake. Since the only force exerted on thetool is the force of the cylinders, the tool can relatively easily beremoved without disassembling the whole device.

The at least one lever and the at least one cam wheel are arranged tocyclically lift the at least one cylinder. This provides an easy way ofcontrolling the cylinders and, thus, the movement of the movingpart/parts connected to the cylinder.

At least two cylinders can be provided, each cylinder being controlledvia a respective lever by a respective cam wheel, the at least two camwheels being arranged on a common rotating cam shaft. This isadvantageous since it makes it possible to use one common drive unit tooperate all the cam wheels, and thus all the moving parts. This iscost-efficient and makes the device easier to operate and service.

The lever can be arranged to abut against the cam wheel at a point whichis located a distance from the fixed end of one third of the distancebetween the fixed end and the cylinder. This has the effect that a risein the cam curve of e.g. 1 cm raises the cylinder 2 cm, thus making itpossible to use very smooth cam curves on the cam wheel. This is anadvantage since it reduces the wear on the cam curves.

The moving parts can comprise at least one of the following:

a first folding unit for folding the fin such that flaps are created atthe sides of it,

a breaking unit for breaking corners on the folded fin,

a second folding unit for folding the flaps against each other,

a pressing unit for pressing down the flaps towards the remaining partof the sleeve,

means for pre-folding the fin,

first means for heating the pre-folded fin,

second means for heating the folded fin,

a first partible forming tool for supporting the package during thepressing down of the flaps.

The invention further concerns a package comprising a sleeve ofpackaging material with a longitudinal seal, and a transversal seal inthe bottom in the shape of a fin, wherein the bottom is folded such that

the fin is folded away from the longitudinal seal,

a middle portion of the fin is folded towards the part of the sleeveforming the bottom, and

the transversal end portions of the fin are folded towards each otherand the middle portion of the fin, wherein

in regions between the sides of the transversal end portions of the fin,and the edges between the part of the sleeve forming the bottom and therest of the sleeve, folds are provided on each side of each transversalend portion and folded towards the fin and the part of the sleeveforming the bottom, in between the transversal end portion and the partof the sleeve forming the bottom, such that the bottom has anessentially octagonal shape. This package has the advantage of anessentially rounded cross-section of the sleeve, due to the octagonalshape of the bottom. This results in a package which is comfortable fora user to hold in his hand while e.g. drinking. The bottom folding isstable and can be produced quickly, which leads to efficient productionof the package.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described below with reference to the accompanyingdrawings, in which

FIG. 1 is a side view of a folding device,

FIG. 2 a shows the first sub-assembly in a perspective view when open,

FIG. 2 b shows the first sub-assembly in a perspective view when closed,

FIG. 3 a shows the second sub-assembly in a first position in aperspective view,

FIG. 3 b shows the second sub-assembly in a second position in aperspective view when closed,

FIG. 3 c shows the second sub-assembly in a third position in aperspective view,

FIG. 4 a shows the third sub-assembly in a perspective view when open,

FIG. 4 b shows the third sub-assembly in a perspective view when closed,

FIG. 4 c shows the third sub-assembly in a perspective view when closedduring pressing-down of the plunger,

FIG. 5 a shows a part of the package which is to be folded from oneside,

FIG. 5 b shows a part of the package which is to be folded from anotherside,

FIG. 5 c shows the package in a perspective view with the bottom foldingportion partly folded,

FIG. 5 d shows the package in a plan view from the bottom when thebottom is folded,

FIG. 6 a shows a cam profile,

FIG. 6 b shows another cam profile,

FIG. 7 a shows a detail of the second sub-assembly on a larger scale,and

FIG. 7 b shows another detail of the second sub-assembly on a largerscale.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

In the following, the operation and different parts of the bottomfolding device will be described. The device is shown without anypackages, but the packages will have the general shape shown in FIGS. 5a-5 d. The bottom folding device 1 in FIG. 1 contains a firstsub-assembly 2, a second sub-assembly 3 and a third sub-assembly 4.According to the shown embodiment of the invention, the folding device 1is designed to operate on two packages in each unit at a time, i.e. innormal production six packages are located within the folding device.Thus, in the drawings, the different units in the folding device 1 areoften shown in pairs of two.

The first sub-assembly 2 is shown in FIGS. 2 a and 2 b. It comprises apre-folding unit 5 and a pre-heating unit 6.

The second sub-assembly 3 is shown in FIGS. 3 a and 3 b. It comprises abreaking unit 7 with knives 7 a, a first folding unit in the form of aplunger 8, and a heating unit 9 with a nozzle 9 a, a connection piece 9b and a supply piece 9 c. In FIGS. 3 a and 3 b brackets 20 and 21 arealso visible which have cam grooves 22 and 23, respectively. Shafts 24are provided on each side of the brackets. A partible forming tool 25,flap supports 34 and a plate 26 are also provided.

The third sub-assembly 4 is shown in FIGS. 4 a and 4 b. It comprises apartible forming tool 10, a pressing unit in the form of a plunger 11and a second folding unit in the form of ploughs 12. In FIGS. 4 a and 4b a cylinder 16, a cam disc 17, a cam shaft 18 and a lever 19 are alsoshown.

FIGS. 5 a and 5 b show the shape of a package 13 which is to be folded.The package 13 comprises a sleeve 14 with a fin 15 with a transversalseal 33 at its one end. The package 13 also has a longitudinal seal 35.FIG. 5 c shows the package with the bottom in a partly folded state. Thepackage 13 has primary flaps 31 and secondary flaps 32. FIG. 5 d showsthe folded bottom of the package.

When in operation, packages 13 are fed into the bottom folding device 1from the left side in FIG. 1 on some sort of conveyor belt (not shown).The packages 13 are arranged “upside down” on the conveyor belt, i.e.standing on their top end on the belt, and may already be filled withthe desired contents, in which case they have a top closure, e.g. aplastic top. At their other, bottom end, oriented upwards and facing thebottom folding device 1, the packages 13 are sealed with a transversalseal 33. Thus, the packages 13 are sealed at the bottom end and possiblyalso filled. The transversal seal 33 forms a fin 15 together with apredetermined portion of the sleeve.

The material of the packages 13 can, for instance, be laminated paper inone or more layers and an aluminium layer can also be provided. A commonmaterial structure comprises from inside out of the package: aninnermost layer of a plastic material, an aluminium layer (so-calledbarrier layer), a paperboard layer and an outer-most layer of a plasticmaterial. The aluminium barrier could, of course, be omitted or replacedby other barrier materials. Moreover, the paperboard layer can also bereplaced by other layers of e.g. a polymer giving the package therequired stiffness.

In FIG. 2 a, the first sub-assembly is shown in an open position, and inFIG. 2 b in a closed position. In the first sub-assembly 2, apre-folding is performed using a pre-folding unit 5. This unit pre-foldsthe fin 15 slightly away from the longitudinal seal 35. Whilepre-folding the fin 15, the pre-heating unit 6 heats the fin 15 where itis folded using e.g. hot air nozzles. This heating makes the layers inthe packaging material more flexible and thereby makes it possible tostretch the material during the pre-folding without any cracks occurringin the layers. It is especially important in case of aseptic packagesthat the aluminum layer not be damaged to such an extent that theaseptic nature of the package is compromised.

Pre-folding the fin 15 in a direction away from the longitudinal seal 35is preferred, but not necessary, since it is more difficult to fold overthe longitudinal seal 22 where a number of layers of packaging materiallie one above the other to make the seal reliable.

Subsequently, the package 13 (or packages, as in the shown example) istransported to the second sub-assembly 3 in which the fin 15 is folded,corners are broken, and the fin 15 is heated in a number of locations.The package 13 is held by the forming tool 25 and the lower portion ofthe flap supports 34 during these operations. The forming tool 25 andthe flap supports 34 together define an octagonal package shape.

A middle portion of the pre-folded fin 15 is pressed down against thepart of the package 13 forming the bottom using a plunger 8. Thisoperation creates a primary flap 31 on each of the two transversal endsof the fin 15. The upper portions of the flap supports 34, which aremounted on the plate 26, flatten the flaps 31 against the plunger 8 whenin their lowest position. To make the final folded package bottom lookattractive it is important for the flaps 31 to be flat. On each side ofeach primary flap 31, in the region between the top end of the flap 31and the edges between the part of the sleeve forming the bottom and therest of the sleeve, the breaking unit 7 acts on the package.

The breaking unit 7 comprises four knives 7 a acting on each package,which knives 7 a are pressed against each said region to create a corneror secondary flap 32 in each region. These secondary flaps 32 are foldedin between the top end of each respective primary flap 31 and thepressed-down middle portion of the fin 15. The package with the primary31 and the secondary 32 flaps is shown in FIG. 5 c. The folding of thesesecondary flaps 32 gives the folded bottom an octagonal shape when thefolding operation is finished, as is shown in FIG. 5 d.

In a number of locations on the fin 15, the packaging material is heatedusing the hot air nozzles 9 a of the heating unit 9 which are movableinto and out of a position where they heat the fin 15. The heatingcauses a plastic layer on the surface of the packaging material on theselocations to melt. During the heating, the primary flaps 31 are held inposition by the flap supports 34 to ascertain that the fin 15 is heatedin the correct locations and that the nozzles 9 a have enough space tobe able to come close to the heating locations. It is important that thehot air nozzles 9 a are close to the desired heating locations duringheating since their effect decreases exponentially according to thedistance.

The hot air is fed to the nozzle 9 a, via a connection piece 9 b, shownin FIG. 7 a, from a supply piece 9 c, shown in FIG. 7 b, which isconnected to a hot air source (not shown). When the hot air nozzle 9 ais moved in and out of the position where it heats the fin, theconnection piece 9 b slides against the supply piece 9 c. The connectionbetween the connection piece 9 b and the supply piece 9 c is a slidingswivel connection, in which a hole 27 in the connection piece 9 b isarranged to slide in an arcuate slot 28 in the supply piece 9 c. The hotair is fed through the slot 28.

The surface 29 around the hole 27 in the connection piece 9 b fitstightly against the surface of the supply piece 9 c, making itimpossible for air to leave the slot 28 anywhere else but through thehole 27 in the connection piece 9 b.

The breaking unit 7 is mounted on a bracket 20 and the forming tool 25is mounted on a bracket 21. The movement of the brackets is controlledby a pair of shafts 24 on each side of the brackets. The shafts aremounted on a plate 26, and, thus, can only move in two directions, i.e.up and down and not sideways. The ends of the shafts 24 slide in camgrooves 22, 23 on each side of each bracket.

The cam grooves 23 on the forming tool bracket 21 have the shape shownin FIG. 6 a and the cam grooves 22 on the breaking unit bracket 20 havethe shape shown in FIG. 6 b. Thus, the breaking unit bracket 20 and theforming tool bracket 21 are controlled by the same shafts but movedifferently since the cam grooves are differently shaped.

The movement of the plunger 8 is separately controlled as is also themovement of the heating unit 9.

The first position for the second sub-assembly is shown in FIG. 3 a.Here, the plunger 8 is up and the forming tool 25 and the breaking unit7 are open. In this position the packages 13 whose bottoms are to befolded are indexed into the sub-assembly.

In FIG. 3 b, the plunger 8 is down and folds the fin to create primaryflaps 31 and the knives 7 a are pressed against the package and foldcorners or secondary flaps 32 on each side of each flap 31, in theregion between the top end of the flap 31 and the edges between the partof the sleeve 14 forming the bottom and the rest of the sleeve 14. Theforming tool 25 retains the package 13 during this operation.

In FIG. 3 c the plunger 8 is up and the knives 7 a are not in contactwith the package 13. The heating unit 9 has moved to a position wherethe hot air nozzles 9 a act on a number of locations on the folded fin15 and at least partly melt a plastic layer on the surface of thepackaging material on these locations. The forming tool 25 still retainsthe package 13. Finally the sub-assembly returns to the position shownin FIG. 3 a.

Subsequently, the packages are indexed to the third sub-assembly 4,where the final folding and sealing of the bottom takes place. In FIG. 4a the third sub-assembly is shown in an open position where the formingtools 10 are open and the ploughs 12 and the plunger 11 are up.

When the package 13, having the shape shown in FIG. 5 c, has arrived tothe third sub-assembly 4, the forming tool 10 is closed around thepackage 13. At the same time the ploughs 12 start to act on the flaps 31and fold them a bit towards the middle portion of the fin 15. Thisposition of the third sub-assembly 4 is shown in FIG. 4 b.

In FIG. 4 c the plunger 11 presses down the flaps 31 completely againstthe folded middle portion of the fin 15, and, thanks to the previousmelting of some locations on the fin, the flaps 31 are then sealed intheir folded position against the fin 15. The bottom of the package 13now has the shape shown in FIG. 5 d. During the pressing-down of theplunger 11, the ploughs 12 remain in the same place since they arearranged to extend through the plunger 11 and not to be affected by itsmovement. The plunger 11 remains pressed against the bottom for a timeperiod of about 50 ms to ensure that the sealing is properly performed.After this, the forming tool 10 is opened and the ploughs 12 lifted awayfrom the package. The plunger 11 is also lifted from the folded andsealed bottom and the package 13 is indexed out of the folding device.

In the following, the system for controlling the movement of thedifferent moving parts in the device will be described. Each of themoving parts in the folding device is connected to a respective cylinder16. Some of the moving parts can be connected to the same cylinder, asis the case with the breaking unit 7 and the forming tool 25.

In FIGS. 4 a and 4 b the cylinder 16 is at one end connected to theplunger 11 in the third sub-assembly 4. The description is, of course,applicable to the other moving parts in the device as well.

The cylinder 16 is arranged to always act downwards and, thus, in theshown example to push the plunger 11 downwards. The cylinder 16 is atthe other end connected to a lever 19, which in turn is secured to afixed point 30 at its other end. The end position of the verticalmovement of the cylinder can be adjusted by an eccentric bushing (notshown) at the fixed point 30. At a distance from the fixed point 30 ofone third of the length of the lever 19, the lever 19 abuts against arotating cam disc 17. The cam disc 17 is mounted on a cam shaft 18 whichcontrols the rotation of the cam disc 17.

The shape and movement of the cam disc 17 in turn controls the movementof the cylinder 16. When the lever 19 abuts against a part of the camdisc 17 which has a larger diameter, as shown in FIGS. 4 a and 4 b, thelever 19 is lifted and in turn lifts the cylinder 16. This in turnraises the moving part connected to the cylinder 16, in this case theplunger 11.

When the lever 19 abuts against a part of the cam disc 17 which has asmaller diameter, as is shown in FIG. 4 c, the lever 19 is lowered andthe cylinder 16 is allowed to push the plunger 11 downwards.

Since the lever 19 abuts against the cam disc 17 at a distance from thefixed point 30 of one third of the total length of the lever 19, a raisein the cam disc 17 by one unit raises the lever end connected to thecylinder 16 by two units. This means that the alterations in thediameter of the cam disc 17 can be small and still effect the desiredalterations in the position of the cylinder 16.

When the moving parts are to be moved essentially laterally in and outof contact with the package 13, the vertical movement of the cylinder 16is converted to at least partly lateral movement via cam grooves inbrackets on which the relevant moving part is mounted. An example ofthis is shown in FIGS. 3 a and 3 b, where the vertical movement of theshaft 24 is converted to at least partly lateral movement of thebrackets 20 and 21.

The three sub-assemblies operate simultaneously on packages. Also, inthe shown embodiment, each of the sub-assemblies are arranged to operateon two packages at the same time, so that the packages are always movedtwo steps at a time to get to the next sub-assembly. It is of coursealso possible to use sub-assemblies which are arranged to operate onone, three, four or any number of packages at the same time. Then, thepackages are of course moved a corresponding number of steps at a time.

Further, even though the invention has been described in connection withparticular embodiments and examples thereof, the scope of the inventionshould not be limited thereto. Various changes and modification may bemade without departing from the scope of the invention, as defined bythe appended claims.

1. A method of folding a bottom of a package, which comprises a sleeve of packaging material with a bottom forming portion of the package, said bottom forming portion having the shape of a fin, the method comprising forming a transversal seal at an end of the bottom forming portion whereby the fin comprises a sealed portion of the transversal seal, after the forming of the transversal seal at the end of the bottom forming portion, pressing a middle of the sealed portion of the fin, thereby folding a middle portion of the fin, such that primary flaps are created at transversal ends of the fin, after the pressing of the middle of the sealed portion of the fin, pressing knives against corners on the folded fin in boundary regions between the primary flaps and an edge between the bottom forming portion of the sleeve and the rest of the sleeve, thereby breaking said corners, such that secondary flaps are folded in between the primary flaps and a remaining part of the fin, the secondary flaps on each side of each primary flap thereby being folded essentially towards each other, after the pressing of the knives against the corners on the folded fin, folding the primary flaps towards each other, and pressing the primary flaps towards the folded middle portion of the fin.
 2. A method according to claim 1, wherein the bottom of the package is folded into an octagonal shape.
 3. A method according to claim 1, wherein the sleeve has a longitudinal seal and the fin is pre-folded away from the longitudinal seal prior to the primary flap-creating folding step.
 4. A method according to claim 3, wherein the fin is heated during the pre-folding.
 5. A method according to claim 1, wherein the fin is heated in a number of locations, where the fin is arranged to be sealed during the pressing step, along its length, prior to the pressing step.
 6. A method according to claim 1, wherein a first partible external forming tool retains the package during the pressing step.
 7. A method according to claim 6, wherein the first partible external forming tool is opened and closed along the contours of a parallelogram.
 8. A method according to claim 1, wherein the sleeve has a circular cross section.
 9. A method according to claim 1, wherein the folding of the primary flaps towards each other comprises pressing ploughs against the primary flaps.
 10. A method according to claim 9, wherein the pressing of the primary flaps towards the folded middle portion of the fin comprises moving a plunger between the ploughs to press the primary flaps. 